Well. I already had suspicions here and there as a player, but not only did I expect things to go that far, but I basically dropped my jaw when Raubahn lost it and went berserk. Finally, someone started taking bloody action on those greedy jerks. Still though, this is just another reason why I hate politics so much.
For those screaming "Who didn't see that coming!? Are you all blind!?", you MUST take into account that we, the player, are being allowed to see things that the characters themselves are not. This even goes for our own character. It would be silly and stupid for all the characters in the game itself to somehow automatically suspect all the things we suspect. Thou must learn the meaning of the art of story telling and how each character sees things individually from us viewers if thou insists on thinking it was so easy of a trap to spot.
That said, I'm going to go ahead and put up a guide for that new Trial battle too in the spoilers below if people are still having trouble with it:
(But before that, let me express my annoyance with the players in the random Duty Roulette finder who rage quit on first or second wipe on a new trial battle that ONLY JUST CAME OUT TODAY. And yet they act as though everything should go flawlessly on the first attempt... on a battle that only been out for maybe... 4 hours or so. Or else... RAGE QUIT! Seriously, to those people, grow some balls yo. Wipes happen, especially on new content that everyone is still learning on the first day.)
Tank Duties: Both tanks run around drawing the attention of the adds and getting them under the main boss, so that the people operating the cannons can shoot both the main boss and the adds. It's not absolutely required, but it does make things easier. Among the adds that spawn, both the later 2 bosses from Stone Vigil HM will spawn as well. Take a wild guess which of them needs to be stunned when they decide to unleash their AoE attack?
Healer Duties: Stay with the freaking Tanks and keep them alive. Heal DPS as needed too, but mainly heal the Tanks. There's a lot of adds in this fight, and it's prudent that the Tanks live of course. Otherwise, them adds will be running everywhere.
DPS Duties: This is a trial battle that'll separate the "Herp! Derp!" DPS players from the competent ones. It is imperative that at LEAST 3 of the DPS need to know how to handle cannons, the snares, and the Dragonslayer towers properly. Any error in timing on the firing of the Dragonslayer will result on you missing out about instantly causing 20% damage/health loss to the main boss.
To break it down for the DPS...
2 DPS need to man the regular cannons at all times. Use them to quickly wipe the adds the Tanks round up and pour into the main boss as well. These cannons now come equipped with a third ability that slows any enemy that steps in the puddle it shoots. In this case, these same said 2 DPS are responsible for handling the snares too, which will be needed during the second and third Dragonslayer towers. Upon the main boss about to unleash its breath attack (huge rectangle AoE blast), it's in range of the snares. Get off the cannons and activate the snares. During part 3, the last stretch, you'll also be presented with... explosives... I'm sure you can figure out what to do with those...
1 DPS needs to man the Dragonslayer towers. You'll see an AoE circle appear on the ground as you get near the weapon trigger. You want the boss to be standing in that circle before firing. The first shot is pretty much free. Just fire when the boss steps into the spot. However, during towers 2 and 3, you'll need to wait until the snares have been thrown onto the main boss. Otherwise... the dragon will literally just jump out of the way of the missile. I know right? It's smart! o.o *Ahem!* Again, wait for the cannon operators to ensnare the main boss before firing the Dragonslayer from towers 2 and 3.
1 DPS... is backup. Unless something happens to any of the other 3 DPS though, the last DPS focuses on... doing regular rotations as a DPS on the main boss. BLM's are preferred in this role due to having access to Flare, allowing the BLM to easily add to the destruction of the adds. BRD's are generally good about this too.
Finally, when the cannons are already destroyed (Do get off them before the main boss destroys them and keep distance from the cannons) and there's nothing else to deal damage to the main boss, everyone just start wailing on the boss until the next set of cannons and tower is available. Or the adds, if any are still standing. Don't be shy about spamming the physical LB3 on the boss too, as this battle is a timed battle for the most part.
If all goes according to plan, you'll have it dead upon reaching phase 3.